Block Timestamp Manipulation

block.timestamp می تواند توسط ماینرها با محدودیت های زیر دستکاری شود

• نمی توان آن را با زمان زودتر از والد خود مهر کرد
• در آینده نمی تواند خیلی دور باشد

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

/*
Roulette is a game where you can win all of the Ether in the contract
if you can submit a transaction at a specific timing.
A player needs to send 10 Ether and wins if the block.timestamp % 15 == 0.
*/

/*
1. Deploy Roulette with 10 Ether
2. Eve runs a powerful miner that can manipulate the block timestamp.
3. Eve sets the block.timestamp to a number in the future that is divisible by
   15 and finds the target block hash.
4. Eve's block is successfully included into the chain, Eve wins the
   Roulette game.
*/

contract Roulette {
    uint256 public pastBlockTime;

    constructor() payable {}

    function spin() external payable {
        require(msg.value == 10 ether); // must send 10 ether to play
        require(block.timestamp != pastBlockTime); // only 1 transaction per block

        pastBlockTime = block.timestamp;

        if (block.timestamp % 15 == 0) {
            (bool sent,) = msg.sender.call{value: address(this).balance}("");
            require(sent, "Failed to send Ether");
        }
    }
}